Dance icon Gene Kelly, whose films are receiving a 24-hour Turner Classic Movies “Summer Under the Stars’’ marathon on Thursday, the 100th anniversary of his birth, is more popular now than he’s been for decades.

Kelli Marshall, a lecturer at DePaul University and the author of “Putting the Ass in Assets: The Objectification of Gene Kelly (and Other Men) on Social Media’’ points to a perfect storm of 21st-century phenomenon, including recent nationwide showings of Kelly’s most famous film, “Singin’ in the Rain,” in theaters to celebrate its 60th anniversary.

He’s also benefited from “the revival of mass audience interest in film musical and dance-themed shows’’ like “Glee’’ and “Dancing With the Stars,’’ Marshall says.

And then there’s that fabulous posterior and what Marshall calls Kelly’s “flexible masculine/effeminate star image that allows viewers to read Kelly and his body in vastly different ways — manly athlete, gay icon and subject of sexy heterosexual fan action.’’

The effect is magnified by social media like Twitter, Facebook and blogs, “which allow fans to collect, redistribute and promote Gene Kelly’s work, photos, etc. with an immediacy and voracity heretofore unseen,’’ Marshall says.

Here are some of the films being shown on TCM:

“Anchors Aweigh’’ (1945), 8 a.m.

Kelly’s first megahit paired him with red-hot crooner Frank Sinatra, playing a pair of sailors who get a four-day leave in Hollywood. Kelly, who received his only Oscar nomination (as Best Actor) for this, had a famous number with MGM’s animated Jerry the Mouse, who was recruited when Walt Disney wouldn’t make Mickey Mouse available.

“Cover Girl’’ (1944), 8 p.m.

After several supporting roles at MGM, Kelly was loaned to Columbia for this Technicolor treat with songs by Jerome Kern that made Kelly a star and Rita Hayworth a superstar as a nightclub owner and fashion model. Kelly also handled the choreography, including his groundbreaking “Alter Ego’’ number. He reprised his role in his last film, “Xanadu,’’ a remake of another Hayworth movie in which he didn’t appear.

“Take Me Out to the Ball Game’’ (1949), 1 p.m.

Busby Berkeley directed this Technicolor bauble about a pair of song- and-dance men (Kelly and Sinatra) turned baseball players whose team is taken over by a nonswimming Esther Williams in the early 20th century. Songs include “O’Brien to Ryan to Goldberg.’’

“An American in Paris’’ (1951), 10 p.m.

Vincente Minnelli’s Gershwin songbook musical with Leslie Caron and Oscar Levant was nominated for 10 Oscars (none for Kelly as actor or choreographer) and won six, including Best Picture. MGM’s marketing executives sought to excise Kelly’s celebrated 20-minute title ballet sequence, but outgoing studio founder Louis B. Mayer fought for its retention.

“On the Town’’ (1949), 6:15 p.m.

The third and final Kelly-Sinatra teaming is their most famous, an adaptation of the Broadway musical filmed partly on location in New York. Kelly, who co-directed with Stanley Donen, is paired with dancer Vera-Ellen, while Sinatra teams in two comic duets with Betty Garrett. Sinatra refused to appear in “It’s Always Fair Weather,’’ originally intended as a sequel, because he didn’t want to have his posterior padded to wear a sailor suit again.

“Inherit the Wind’’ (1960), 2 a.m.

In one of his many nonmusicals, Kelly has a supporting role in Stanley Kramer’s adaptation of the Jerome Lawrence-Robert Lee play as a reporter covering the 1925 trial over the teaching of evolution pitting Spencer Tracy and Frederic March as fictionalized versions of Clarence Darrow and William Jennings Bryan.